In many areas of the world, seismic activity, such as earthquakes, presents a substantial risk to inhabitants of such areas. While low level seismic activity is virtually continuous over the earth surface, major earthquakes often cause great human injury and property damage. Despite great advances in other sciences, the science of geology has yet to produce an effective method by which geologists can predict the locations and times of occurrences of earthquakes. As a result, the typical earthquake occurs suddenly and unexpectedly and, for the most part, takes the victims by surprise.
The sudden, unexpected and often violent character of earthquakes causes substantial fear among many persons living in so-called earthquake prone areas. In fact, the fear of earthquakes exceeds the actual danger or risk in many instances. Earthquakes occurring at night are particularly frightening. Most people subjected to a nighttime earthquake find themselves jolted from a sound sleep into the terror of a violently shaking dwelling and confusing noises such as items being toppled or broken all around them. Such persons often become panicked or frantic as they stumble about in the dark groping for light switches and/or phones to summon help or get information.
In response to these problems, practitioners in the art have endeavored to provide various seismically responsive safety lights or alarm systems. For example, U.S. Pat. No. 5,307,054 issued to Concannon, Sr., et al. sets forth a motion sensor circuit controller having a ring-shaped first conductor, a second conductor defining a concave conductive surface, a base for supporting the first conductor horizontally oriented above the second conductor with the first and second conductors being connected within a circuit. A conductive ball rollably contacts the second conductor and makes electrical contact between the first and second conductors in response to lateral movement of the conductor. The electrical contact between first and second conductors is used to operate various devices such as a battery-power flashlight or the like. This system is subject to several substantial limitations rendering impractical aspects when considered in a practical manufacturing environment. For example, the unit must be disassembled and other combinations of the ball 16, the inside diameter of ring 18 and the concavity of the screen 42 can be selected for producing the same sensitivity or other desired sensitivities. Further, the triggering of the alarm or light requires that four electrical contacts be completed. The system is extremely demanding on contact actuation and thus high cost gold plated contacts are required. Also, the units shown in this patent are not suitable for use in installations such as wall-mounted or the like.
U.S. Pat. No. 4,359,722 issued to Valdez, et al. sets forth a EARTHQUAKE DETECTION SYSTEM WITH PENDULUM SWITCH having a suspended pendulum which at its lower end has an electric contact space from a stationary ring-shaped contact which surrounds the pendulum contact. During an earth tremor, the stationary contact moves in response to earth motion thereby engaging the suspended pendulum contact and accordingly closing an electric circuit with audible alarm.
U.S. Pat. No. 4,353,383 issued to Kiesel sets forth a SEISMICALLY ACTUATED VALVE RELEASE STRUCTURE for automatically closing or opening a valve upon the occurrence of an earthquake. The release mechanism includes a pendulum which is biased upwardly against stop means formed for pivotal contact with an upper end of the pendulum. The stop means and the upper end have relatively small contact area. Biasing means urge a closure member within the valve toward an open or closed position and the closure member is releasibly retained against the urging of the biasing means by a latch.
U.S. Pat. No. 4,585,358 issued to Shay sets forth a SHAKEABLE SHUT-OFF ALARM CLOCK having a standard alarm configured to be silenced by lateral shaking of the clock. The silencing mechanism includes a laterally shakeable switch responsive to clock motion.
U.S. Pat. No. 5,307,699 issued to Engdahl, et al. sets forth a SEISMIC INITIATOR FOR EARTHQUAKE SHUT-OFF VALVES AND THE LIKE having an acceleration responsive magnet device for closing a valve or operating a switch or the like in response to a disturbance such as an earthquake. A pendulum operates to increase the length of a magnetic path releasing a magnetic element to perform the desired actuation.
U.S. Pat. No. 5,278,540 issued to Caban-Domenech sets forth an ELECTROMECHANICAL EARTHQUAKE ALARM having an earthquake sensor in which a weight falls from a support surface and activates a switch in the event of an earthquake. The support surface is preferably a bell with its open end oriented downward and the weight resting on a concave recessed region at the closed end of the bell.
U.S. Pat. No. 4,103,697 issued to Kiesow sets forth a SAFETY SENSOR DEVICE for automatically shutting off the flow of fluids such as water, gas, oil or steam or for shutting off electric power or actuating an alarm in the event of an earthquake. The device includes a spring-loaded shutoff member normally held in a retracted position by a latch. A pendulum is connected to the latch such that upon the occurrence of an earthquake, movement of the pendulum occurs releasing the latch.
While the foregoing prior art devices have improved the art and, in some instances, enjoyed commercial success, they have failed to provide a seismically activated switch which is suitable for use in attachment to a structure wall. For the most part, such prior art devices have lacked sufficient sensitivity in all force directions. Thus, there remains nonetheless a continuing need in the art for evermore effective reliable, simple to operate seismically activated appliance switching apparatus.